Rework single-value set-credentials-library logic (#1364)

internal/cmd/commands/targetscmd/funcs.go

@@ -324,14 +324,18 @@ func extraFlagsHandlingFuncImpl(c *Command, _ *base.FlagSets, opts *[]targets.Op
 
 	case "set-credential-libraries":
 		// TODO: As we add other purposes, add them to this check
-		if len(c.flagApplicationCredentialLibraries) == 0 {
+		switch len(c.flagApplicationCredentialLibraries) {
+		case 0:
 			c.UI.Error("No credential-libraries supplied via -application-credential-library")
 			return false
-		}
-		*opts = append(*opts, targets.WithApplicationCredentialLibraryIds(c.flagApplicationCredentialLibraries))
-		if len(c.flagApplicationCredentialLibraries) == 1 && c.flagApplicationCredentialLibraries[0] == "null" {
-			// Clear all library ids since the only value set is a null.
-			*opts = append(*opts, targets.DefaultApplicationCredentialLibraryIds())
+		case 1:
+			if c.flagApplicationCredentialLibraries[0] == "null" {
+				*opts = append(*opts, targets.DefaultApplicationCredentialLibraryIds())
+				break
+			}
+			fallthrough
+		default:
+			*opts = append(*opts, targets.WithApplicationCredentialLibraryIds(c.flagApplicationCredentialLibraries))
 		}
 
 	case "authorize-session":