Error reporting behaviour inconsistent with previous Halide

[TH3CHARLie]

As discussed offline, open as a tracking issue.

Previously, if an internal_assert(cond was triggered the error message was something like Unhandled exception: Internal Error at Halide/src/Schedule.cpp:348 triggered by user code at: Condition failed which tells you exactly the assertion is and is super helpful for locating the crash site.

With ecent PR: #8627, same internal_assert error message becomes Error:. An explict HL_DEBUG_CODEGEN=1 is required to see the crash site diagnosis. This is inconsitent with previous Halide.

cc @alexreinking @abadams

[alexreinking]

With ecent PR: #8627, same internal_assert error message becomes Error:. An explict HL_DEBUG_CODEGEN=1 is required to see the crash site diagnosis. This is inconsitent with previous Halide.

Actually, this bug was introduced earlier (still by me) in #8564