Add a crash test to mono

crates/compiler/test_mono/src/tests.rs

@@ -2035,11 +2035,16 @@ fn recursive_function_and_union_with_inference_hole() {
 fn crash() {
     indoc!(
         r#"
-        app "test" provides [getInfallible] to "./platform"
+        app "test" provides [main] to "./platform"
 
         getInfallible = \result -> when result is
             Ok x -> x
             _ -> crash "turns out this was fallible"
+
+        main =
+            x : [Ok U64, Err Str]
+            x = Ok 78
+            getInfallible x
         "#
     )
 }