fix: do not panic on ref types while safepoint disabled

cranelift/codegen/src/regalloc/context.rs

@@ -212,7 +212,11 @@ impl Context {
             for val in func.dfg.values() {
                 let ty = func.dfg.value_type(val);
                 if ty.lane_type().is_ref() {
-                    panic!("reference types were found but safepoints were not enabled.");
+                    errors.report((
+                        val,
+                        "reference types were found but safepoints were not enabled.",
+                    ));
+                    return Err(errors.into());
                 }
             }
         }

cranelift/filetests/filetests/verifier/ref-safepoint.clif

@@ -0,0 +1,13 @@
+test safepoint
+test verifier
+target x86_64
+
+function %test(r64) -> r64 {  
+    block0(v0: r64): 
+        v1 = null.r64
+        v2 = is_null v0 
+        brz v2, block2(v0)
+        jump block2(v1)
+    block2(v3: r64): 
+        return v3
+}