[Wasm] Instantiate error detection (#128167)

Better failure mode when trying to load an R2R module using a release build of corerun.js.

Author: kg

src/coreclr/hosts/corerun/wasm/libCorerun.js

@@ -220,6 +220,9 @@ function libCoreRunFactory() {
                 if (_posix_memalign(ptrPtr, 16, payloadSize)) {
                     throw new Error("posix_memalign failed for Webcil payload");
                 }
+                if (typeof (wasmExports.__stack_pointer) === "undefined") {
+                    throw new Error("__stack_pointer was not preserved by the linker or optimizer");
+                }
                 payloadPtr = HEAPU32[ptrPtr >>> 2 >>> 0];
                 wasmInstance = new WebAssembly.Instance(wasmModule, {
                     webcil: {
@@ -229,6 +232,10 @@ function libCoreRunFactory() {
                         tableBase: new WebAssembly.Global({ value: "i32", mutable: false }, tableStartIndex),
                         imageBase: new WebAssembly.Global({ value: "i32", mutable: false }, payloadPtr)
                     }});
+            } catch (e) {
+                const errorMessage = e instanceof Error ? e.message : String(e);
+                console.error("Failed to construct WebAssembly instance for Webcil image:", {wasmPath, errorMessage});
+                return false;
             } finally {
                 stackRestore(sp);
             }