Ensure we have an import error before using in import path (#5884)

Without this, we can panic

CHANGELOG.md

@@ -2,7 +2,9 @@ CHANGELOG
 =========
 
 ## HEAD (Unreleased)
-_(none)_
+
+- Fix a problem where `pulumi import` could panic on an import error due to missing error message. 
+  [#5884](https://github.com/pulumi/pulumi/pull/5884)
 
 ## 2.15.3 (2020-12-07)
 

pkg/resource/deploy/deployment_executor.go

@@ -456,7 +456,7 @@ func (ex *deploymentExecutor) importResources(callerCtx context.Context, opts Op
 	canceled := callerCtx.Err() != nil
 
 	if res != nil || stepExec.Errored() {
-		if res.Error() != nil {
+		if res != nil && res.Error() != nil {
 			ex.reportExecResult(fmt.Sprintf("failed: %s", res.Error()), preview)
 		} else {
 			ex.reportExecResult("failed", preview)