Improve assertion violation message (#22522)

Author: weswigham

src/compiler/binder.ts

@@ -301,7 +301,7 @@ namespace ts {
                 case SyntaxKind.Parameter:
                     // Parameters with names are handled at the top of this function.  Parameters
                     // without names can only come from JSDocFunctionTypes.
-                    Debug.assert(node.parent.kind === SyntaxKind.JSDocFunctionType);
+                    Debug.assert(node.parent.kind === SyntaxKind.JSDocFunctionType, "Impossible parameter parent kind", () => `parent is: ${(ts as any).SyntaxKind ? (ts as any).SyntaxKind[node.parent.kind] : node.parent.kind}, expected JSDocFunctionType`);
                     const functionType = <JSDocFunctionType>node.parent;
                     const index = functionType.parameters.indexOf(node as ParameterDeclaration);
                     return "arg" + index as __String;