Fix seg fault

Check types before accessing typeName.

Fix #2848.

Test/noMatchingFunction.frag

@@ -0,0 +1,19 @@
+#version 330
+
+struct S
+{
+	float a;
+};
+
+float func(S s)
+{
+	return s.a;
+}
+
+layout(location = 0) out vec4 o_color;
+
+void main()
+{
+	float c = func(1.0f); // ERROR: no matching function
+	o_color = vec4(c);
+}