Added more tests

tests/errors/UnknownIdentifier3.q

@@ -0,0 +1,3 @@
+main() {
+	x := 1 + f(x)
+}

tests/errors/UnknownIdentifier4.q

@@ -0,0 +1,7 @@
+main() {
+	x := 1 + f(x)
+}
+
+f(x) {
+	return x
+}

tests/errors_test.go

@@ -35,6 +35,8 @@ var errs = []struct {
 	{"VariableAlreadyExists.q", &errors.VariableAlreadyExists{Name: "x"}},
 	{"UnknownIdentifier.q", &errors.UnknownIdentifier{Name: "x"}},
 	{"UnknownIdentifier2.q", &errors.UnknownIdentifier{Name: "x"}},
+	{"UnknownIdentifier3.q", &errors.UnknownIdentifier{Name: "f"}},
+	{"UnknownIdentifier4.q", &errors.UnknownIdentifier{Name: "x"}},
 	{"UnusedVariable.q", &errors.UnusedVariable{Name: "x"}},
 }