diff --git a/crates/wac-types/src/core.rs b/crates/wac-types/src/core.rs
index 87de30d..67fdbeb 100644
--- a/crates/wac-types/src/core.rs
+++ b/crates/wac-types/src/core.rs
@@ -111,15 +111,17 @@ impl fmt::Display for CoreExtern {
     }
 }
 
-impl From<wasmparser::TableType> for CoreExtern {
-    fn from(ty: wasmparser::TableType) -> Self {
-        Self::Table {
-            element_type: ty.element_type.into(),
+impl TryFrom<wasmparser::TableType> for CoreExtern {
+    type Error = anyhow::Error;
+
+    fn try_from(ty: wasmparser::TableType) -> anyhow::Result<Self> {
+        Ok(Self::Table {
+            element_type: ty.element_type.try_into()?,
             initial: ty.initial,
             maximum: ty.maximum,
             table64: ty.table64,
             shared: ty.shared,
-        }
+        })
     }
 }
 
@@ -135,13 +137,15 @@ impl From<wasmparser::MemoryType> for CoreExtern {
     }
 }
 
-impl From<wasmparser::GlobalType> for CoreExtern {
-    fn from(ty: wasmparser::GlobalType) -> Self {
-        Self::Global {
-            val_type: ty.content_type.into(),
+impl TryFrom<wasmparser::GlobalType> for CoreExtern {
+    type Error = anyhow::Error;
+
+    fn try_from(ty: wasmparser::GlobalType) -> anyhow::Result<Self> {
+        Ok(Self::Global {
+            val_type: ty.content_type.try_into()?,
             mutable: ty.mutable,
             shared: ty.shared,
-        }
+        })
     }
 }
 
@@ -177,16 +181,18 @@ impl fmt::Display for CoreType {
     }
 }
 
-impl From<wasmparser::ValType> for CoreType {
-    fn from(ty: wasmparser::ValType) -> Self {
-        match ty {
+impl TryFrom<wasmparser::ValType> for CoreType {
+    type Error = anyhow::Error;
+
+    fn try_from(ty: wasmparser::ValType) -> anyhow::Result<Self> {
+        Ok(match ty {
             wasmparser::ValType::I32 => Self::I32,
             wasmparser::ValType::I64 => Self::I64,
             wasmparser::ValType::F32 => Self::F32,
             wasmparser::ValType::F64 => Self::F64,
             wasmparser::ValType::V128 => Self::V128,
-            wasmparser::ValType::Ref(ty) => Self::Ref(ty.into()),
-        }
+            wasmparser::ValType::Ref(ty) => Self::Ref(ty.try_into()?),
+        })
     }
 }
 
@@ -253,12 +259,14 @@ impl fmt::Display for CoreRefType {
     }
 }
 
-impl From<wasmparser::RefType> for CoreRefType {
-    fn from(ty: wasmparser::RefType) -> Self {
-        Self {
+impl TryFrom<wasmparser::RefType> for CoreRefType {
+    type Error = anyhow::Error;
+
+    fn try_from(ty: wasmparser::RefType) -> anyhow::Result<Self> {
+        Ok(Self {
             nullable: ty.is_nullable(),
-            heap_type: ty.heap_type().into(),
-        }
+            heap_type: ty.heap_type().try_into()?,
+        })
     }
 }
 
@@ -316,9 +324,11 @@ pub enum HeapType {
     NoCont,
 }
 
-impl From<wasmparser::HeapType> for HeapType {
-    fn from(ty: wasmparser::HeapType) -> Self {
-        match ty {
+impl TryFrom<wasmparser::HeapType> for HeapType {
+    type Error = anyhow::Error;
+
+    fn try_from(ty: wasmparser::HeapType) -> anyhow::Result<Self> {
+        Ok(match ty {
             wasmparser::HeapType::Abstract { shared: false, ty } => match ty {
                 wasmparser::AbstractHeapType::Any => Self::Any,
                 wasmparser::AbstractHeapType::Func => Self::Func,
@@ -336,15 +346,15 @@ impl From<wasmparser::HeapType> for HeapType {
                 wasmparser::AbstractHeapType::NoCont => Self::NoCont,
             },
             wasmparser::HeapType::Abstract { shared: true, ty } => {
-                panic!("shared heap types are not supported: {:?}", ty)
+                anyhow::bail!("shared heap types are not supported: {ty:?}")
             }
             wasmparser::HeapType::Concrete(index) => {
                 Self::Concrete(index.as_module_index().unwrap())
             }
             wasmparser::HeapType::Exact(_) => {
-                todo!("wasmparser::HeapType::Exact");
+                anyhow::bail!("exact heap types are not yet supported")
             }
-        }
+        })
     }
 }
 
diff --git a/crates/wac-types/src/package.rs b/crates/wac-types/src/package.rs
index af6a923..0ba9f76 100644
--- a/crates/wac-types/src/package.rs
+++ b/crates/wac-types/src/package.rs
@@ -462,14 +462,16 @@ impl<'a> TypeConverter<'a> {
         let imports = module_ty
             .imports
             .iter()
-            .map(|((module, name), ty)| ((module.clone(), name.clone()), self.entity_type(*ty)))
-            .collect();
+            .map(|((module, name), ty)| {
+                Ok(((module.clone(), name.clone()), self.entity_type(*ty)?))
+            })
+            .collect::<Result<_>>()?;
 
         let exports = module_ty
             .exports
             .iter()
-            .map(|(name, ty)| (name.clone(), self.entity_type(*ty)))
-            .collect();
+            .map(|(name, ty)| Ok((name.clone(), self.entity_type(*ty)?)))
+            .collect::<Result<_>>()?;
 
         let module_id = self.types.add_module_type(ModuleType { imports, exports });
         self.cache
@@ -803,25 +805,35 @@ impl<'a> TypeConverter<'a> {
         resource_id
     }
 
-    fn entity_type(&self, ty: wasmparser::types::EntityType) -> CoreExtern {
-        match ty {
-            wasmparser::types::EntityType::Func(ty) => CoreExtern::Func(self.func_type(ty)),
-            wasmparser::types::EntityType::Table(ty) => ty.into(),
+    fn entity_type(&self, ty: wasmparser::types::EntityType) -> Result<CoreExtern> {
+        Ok(match ty {
+            wasmparser::types::EntityType::Func(ty) => CoreExtern::Func(self.func_type(ty)?),
+            wasmparser::types::EntityType::Table(ty) => ty.try_into()?,
             wasmparser::types::EntityType::Memory(ty) => ty.into(),
-            wasmparser::types::EntityType::Global(ty) => ty.into(),
-            wasmparser::types::EntityType::Tag(ty) => CoreExtern::Tag(self.func_type(ty)),
+            wasmparser::types::EntityType::Global(ty) => ty.try_into()?,
+            wasmparser::types::EntityType::Tag(ty) => CoreExtern::Tag(self.func_type(ty)?),
             wasmparser::types::EntityType::FuncExact(_) => {
                 todo!("wasmparser::types::EntityType::FuncExact")
             }
-        }
+        })
     }
 
-    fn func_type(&self, ty: wasmparser::types::CoreTypeId) -> CoreFuncType {
+    fn func_type(&self, ty: wasmparser::types::CoreTypeId) -> Result<CoreFuncType> {
         let func_ty = self.wasm_types[ty].unwrap_func();
-        CoreFuncType {
-            params: func_ty.params().iter().copied().map(Into::into).collect(),
-            results: func_ty.results().iter().copied().map(Into::into).collect(),
-        }
+        Ok(CoreFuncType {
+            params: func_ty
+                .params()
+                .iter()
+                .copied()
+                .map(TryInto::try_into)
+                .collect::<Result<_>>()?,
+            results: func_ty
+                .results()
+                .iter()
+                .copied()
+                .map(TryInto::try_into)
+                .collect::<Result<_>>()?,
+        })
     }
 
     fn find_owner(&self, mut id: wasm::ComponentAnyTypeId) -> Option<&(Owner, String)> {
diff --git a/crates/wac-types/tests/heap_type_conversion.rs b/crates/wac-types/tests/heap_type_conversion.rs
new file mode 100644
index 0000000..0414f90
--- /dev/null
+++ b/crates/wac-types/tests/heap_type_conversion.rs
@@ -0,0 +1,48 @@
+use wac_types::HeapType;
+
+#[test]
+fn shared_heap_type_returns_error() {
+    let shared_heap = wasmparser::HeapType::Abstract {
+        shared: true,
+        ty: wasmparser::AbstractHeapType::Func,
+    };
+
+    let result: Result<HeapType, _> = shared_heap.try_into();
+    assert!(
+        result.is_err(),
+        "shared heap types should return an error, not panic"
+    );
+    let err = result.unwrap_err().to_string();
+    assert!(
+        err.contains("shared heap types are not supported"),
+        "error should mention shared heap types: {err}"
+    );
+}
+
+#[test]
+fn exact_heap_type_returns_error() {
+    let exact_heap = wasmparser::HeapType::Exact(wasmparser::UnpackedIndex::Module(0));
+
+    let result: Result<HeapType, _> = exact_heap.try_into();
+    assert!(
+        result.is_err(),
+        "exact heap types should return an error, not panic"
+    );
+    let err = result.unwrap_err().to_string();
+    assert!(
+        err.contains("not yet supported"),
+        "error should mention unsupported: {err}"
+    );
+}
+
+#[test]
+fn non_shared_heap_type_succeeds() {
+    let heap = wasmparser::HeapType::Abstract {
+        shared: false,
+        ty: wasmparser::AbstractHeapType::Func,
+    };
+
+    let result: Result<HeapType, _> = heap.try_into();
+    assert!(result.is_ok(), "non-shared heap types should convert fine");
+    assert_eq!(result.unwrap(), HeapType::Func);
+}