This commit replaces most panics in interp/frame.go and interp/scan.go
with real error messages. The remaining ones are panics that should not
happen when working with valid IR.
This is really just a simple workaround. When such an instruction is
encountered, it will just fall back to marking the entire function as
having side effects. Ideally it should trace all affected instructions
and check if they would have any side effects, but this at least fixes a
number of compile errors.
This commit gets the following packages to compile:
* context
* database/sql/driver
* image/jpeg
* image/png
Declarations would enter an infinite loop when trying to loop over basic
blocks. That was probably an undefined operation, but still somehow
didn't crash the compiler.
Make sure that scanning declarations works as expected.
