check move target module exists

We already check if a move target resource still exists, but it's
possible the entire module no longer exists.

internal/refactoring/move_statement.go

@@ -64,27 +64,29 @@ func findMoveStatements(cfg *configs.Config, into []MoveStatement) []MoveStateme
 
 		// We have the statement, let's see if we should attach a provider to
 		// it.
-
 		if toResource, ok := mc.To.ConfigMoveable(addrs.RootModule).(addrs.ConfigResource); ok {
 			// Only attach providers if we are moving resources, and we attach
 			// the to resource provider from the config. We can retrieve the
 			// from resource provider from the state later.
+			modCfg := cfg.Descendent(toResource.Module)
+			// It's possible that multiple refactorings have left a moved block
+			// that points to a module which no longer exists. This may also be
+			// a mistake, but the user will see the unexpected deletion in the
+			// plan if it is.
+			if modCfg != nil {
+				resourceConfig := modCfg.Module.ResourceByAddr(toResource.Resource)
+				if resourceConfig != nil {
+					// Check the target resource config actually exists before we
+					// try and extract the provider from them.
+
+					stmt.Provider = &addrs.AbsProviderConfig{
+						Module:   modAddr,
+						Provider: resourceConfig.Provider,
+					}
 
-			resourceConfig := cfg.Descendent(toResource.Module).Module.ResourceByAddr(toResource.Resource)
-			if resourceConfig != nil {
-
-				// Check the target resource config actually exists before we
-				// try and extract the provider from them. If the resource
-				// doesn't exist in config, then we'll get a validation error
-				// later on anyway.
-
-				stmt.Provider = &addrs.AbsProviderConfig{
-					Module:   modAddr,
-					Provider: resourceConfig.Provider,
-				}
-
-				if resourceConfig.ProviderConfigRef != nil {
-					stmt.Provider.Alias = resourceConfig.ProviderConfigRef.Alias
+					if resourceConfig.ProviderConfigRef != nil {
+						stmt.Provider.Alias = resourceConfig.ProviderConfigRef.Alias
+					}
 				}
 			}
 		}

internal/refactoring/testdata/move-statement-implied/move-statement-implied.tf

@@ -52,3 +52,8 @@ resource "foo" "ambiguous" {
 module "child" {
   source = "./child"
 }
+
+moved {
+  from = foo.already_moved
+  to = module.no_longer_exists.foo.already_moved
+}