fix panic when import id is empty string

We can only detect this during evaluation since the import id
is an hcl expression.

Fixes #33505

internal/terraform/eval_import.go

@@ -72,6 +72,15 @@ func evaluateImportIdExpression(expr hcl.Expression, ctx EvalContext, keyData in
 		})
 	}
 
+	if importId == "" {
+		return "", diags.Append(&hcl.Diagnostic{
+			Severity: hcl.DiagError,
+			Summary:  "Invalid import id argument",
+			Detail:   fmt.Sprintf("The import ID value is \"\", please provide a valid value."),
+			Subject:  expr.Range().Ptr(),
+		})
+	}
+
 	return importId, diags
 }