Compiler error instead of crash for too few args to constructor in ca…

…se pattern.

src/libponyc/expr/match.c

@@ -156,6 +156,10 @@ static ast_t* make_pattern_type(pass_opt_t* opt, ast_t* pattern)
 
   // Structural equality, pattern.eq(match).
   ast_t* pattern_type = ast_type(pattern);
+
+  if(is_typecheck_error(pattern_type))
+    return NULL;
+
   ast_t* fun = lookup(opt, pattern, pattern_type, stringtab("eq"));
 
   if(fun == NULL)

test/libponyc/badpony.cc

@@ -499,3 +499,18 @@ TEST_F(BadPonyTest, CapSetInConstraintTypeParam)
   TEST_ERRORS_1(src,
     "a capability set can only appear in a type constraint");
 }
+
+TEST_F(BadPonyTest, MatchCasePatternConstructorTooFewArguments)
+{
+  const char* src =
+    "class C\n"
+    "  new create(key: String) => None\n"
+
+    "primitive Foo\n"
+    "  fun apply(c: (C | None)) =>\n"
+    "    match c\n"
+    "    | C => None\n"
+    "    end";
+
+  TEST_ERRORS_1(src, "not enough arguments");
+}