Crash when using `this` in a static fn

[h3r2tic]

Issue Description

When you explicitly use this in a static member function of a struct, Slang crashes.

Reproducer Code

struct Foo {
    int a;

    static int func() {
        return this.a;
    }
}

Expected Behavior

A compiler error is reported. Note that this is already the case if this. is implicit instead.

Actual Behavior

Segfault:

#0  0x00007fb924751148 _ZN5Slang15PeepholeContext11processInstEPNS_6IRInstE (libslang-compiler.so.0.2025.24.3 + 0x751148)
#1  0x00007fb92475377f _ZN5Slang15PeepholeContext11processFuncEPNS_6IRInstE (libslang-compiler.so.0.2025.24.3 + 0x75377f)
#2  0x00007fb92474ce8f _ZN5Slang16peepholeOptimizeEPNS_13TargetProgramEPNS_8IRModuleENS_27PeepholeOptimizationOptionsE (libslang-compiler.so.0.2025.24.3 + 0x74ce8f)
#3  0x00007fb9248b8f76 _ZN5Slang28generateIRForTranslationUnitEPNS_10ASTBuilderEPNS_22TranslationUnitRequestE (libslang-compiler.so.0.2025.24.3 + 0x8b8f76)
#4  0x00007fb924446211 _ZN5Slang22FrontEndCompileRequest10generateIREv (libslang-compiler.so.0.2025.24.3 + 0x446211)
#5  0x00007fb92444c86f _ZN5Slang22FrontEndCompileRequest19executeActionsInnerEv (libslang-compiler.so.0.2025.24.3 + 0x44c86f)
#6  0x00007fb92455de7a _ZN5Slang22EndToEndCompileRequest19executeActionsInnerEv (libslang-compiler.so.0.2025.24.3 + 0x55de7a)
#7  0x00007fb92455ef3d _ZN5Slang22EndToEndCompileRequest14executeActionsEv (libslang-compiler.so.0.2025.24.3 + 0x55ef3d)
#8  0x00007fb92455f066 _ZN5Slang22EndToEndCompileRequest7compileEv (libslang-compiler.so.0.2025.24.3 + 0x55f066)

Environment

• Slang Version: 2025.21.2, 2025.24.3
• OS: Linux 6.18.2-arch2-1 x86_64