fuzzgen: Panic on failed NaN Canonicalization pass (#4896)

This should never fail anyway, but it's good to know that we
aren't accidentally ignoring an input

cranelift/fuzzgen/src/lib.rs

@@ -166,7 +166,7 @@ where
         Ok(inputs)
     }
 
-    fn run_func_passes(&self, func: Function) -> Result<Function> {
+    fn run_func_passes(&self, func: Function) -> Function {
         // Do a NaN Canonicalization pass on the generated function.
         //
         // Both IEEE754 and the Wasm spec are somewhat loose about what is allowed
@@ -189,16 +189,18 @@ where
         let flags = settings::Flags::new(settings::builder());
         let isa = builder_with_options(false)
             .expect("Unable to build a TargetIsa for the current host")
-            .finish(flags)?;
+            .finish(flags)
+            .expect("Failed to build TargetISA");
 
-        ctx.canonicalize_nans(isa.as_ref())?;
+        ctx.canonicalize_nans(isa.as_ref())
+            .expect("Failed validation after NaN canonicalization");
 
-        Ok(ctx.func)
+        ctx.func
     }
 
     fn generate_func(&mut self) -> Result<Function> {
         let func = FunctionGenerator::new(&mut self.u, &self.config).generate()?;
-        self.run_func_passes(func)
+        Ok(self.run_func_passes(func))
     }
 
     pub fn generate_test(mut self) -> Result<TestCase> {