terraform: IsSet can be called on nil

terraform/resource_provider.go

@@ -129,6 +129,10 @@ func (c *ResourceConfig) Get(k string) (interface{}, bool) {
 // raw configuration itself, since a key may be omitted from the raw
 // configuration if it is being computed.
 func (c *ResourceConfig) IsSet(k string) bool {
+	if c == nil {
+		return false
+	}
+
 	for _, ck := range c.ComputedKeys {
 		if ck == k {
 			return true

terraform/resource_provider_test.go

@@ -167,3 +167,11 @@ func TestResourceConfig_IsSet(t *testing.T) {
 		}
 	}
 }
+
+func TestResourceConfig_IsSet_nil(t *testing.T) {
+	var rc *ResourceConfig
+
+	if rc.IsSet("foo") {
+		t.Fatal("bad")
+	}
+}