errors on missing packages suggests project update

Signed-off-by: Richard Jones <richard@dagger.io>

plan/plan.go

@@ -49,8 +49,12 @@ func Load(ctx context.Context, cfg Config) (*Plan, error) {
 	if err != nil {
 		errstring := err.Error()
 
-		if strings.Contains(errstring, "cannot find package") && strings.Contains(errstring, "alpha.dagger.io") {
+		if strings.Contains(errstring, "cannot find package") {
-			return nil, ErrIncompatiblePlan
+			if strings.Contains(errstring, "alpha.dagger.io") {
+				return nil, ErrIncompatiblePlan
+			} else if strings.Contains(errstring, pkg.DaggerModule) || strings.Contains(errstring, pkg.UniverseModule) {
+				return nil, fmt.Errorf("%w: running `dagger project update` may resolve this", err)
+			}
 		}
 
 		return nil, err

tests/plan.bats

@@ -46,6 +46,11 @@ setup() {
   assert_output --partial "attempting to load a dagger 0.1.0 project."
 }
 
+@test "plan/do: missing packages suggests project update" {
+  run "$DAGGER" "do" -p ./plan/do/missing_dependencies.cue test
+  assert_output --partial ": running \`dagger project update\` may resolve this"
+}
+
 @test "plan/hello" {
   # Europa loader handles the cwd differently, therefore we need to CD into the tree at or below the parent of cue.mod
   cd "$TESTDIR"

tests/plan/do/missing_dependencies.cue

@@ -0,0 +1,7 @@
+package main
+
+import (
+	"dagger.io/daggggger" // intentionally misspelled to force error message
+)
+
+dagger.#Plan