fix: handle ujson surrogate parse exceptions in JSON imports

sjsonnet/src/sjsonnet/Importer.scala

@@ -380,9 +380,21 @@ object CachedResolver {
       case _: ujson.ParsingFailedException | _: DuplicateJsonKey | _: InvalidJsonNumber |
           _: JsonParseDepthExceeded | _: NumberFormatException =>
         None
+      case e: Exception if isInvalidJsonSurrogateException(e) =>
+        None
     }
   }
 
+  private def isInvalidJsonSurrogateException(e: Exception): Boolean = {
+    if (e.getClass != classOf[Exception]) return false
+    val message = e.getMessage
+    message != null && (
+      message.startsWith("Unexpected character following high surrogate") ||
+      message.startsWith("Duplicate high surrogate") ||
+      message.startsWith("Un-paired low surrogate")
+    )
+  }
+
   private final class JsonImportVisitor(
       fileScope: FileScope,
       internedStrings: mutable.HashMap[String, String],

sjsonnet/test/resources/new_test_suite/error.import_json_lone_low_surrogate.json

@@ -0,0 +1 @@
+{"key": "before\uDC00after"}

sjsonnet/test/resources/new_test_suite/error.import_json_lone_low_surrogate.jsonnet

@@ -0,0 +1 @@
+import 'error.import_json_lone_low_surrogate.json'

sjsonnet/test/resources/new_test_suite/error.import_json_lone_low_surrogate.jsonnet.golden

@@ -0,0 +1,2 @@
+sjsonnet.ParseError: Expected "\"":1:16, found "\\uDC00afte"
+    at [<root>].(error.import_json_lone_low_surrogate.jsonnet:1:1)

sjsonnet/test/resources/new_test_suite/error.import_json_reversed_surrogate.json

@@ -0,0 +1 @@
+{"key": "\uDE00\uD83D"}

sjsonnet/test/resources/new_test_suite/error.import_json_reversed_surrogate.jsonnet

@@ -0,0 +1 @@
+import 'error.import_json_reversed_surrogate.json'

sjsonnet/test/resources/new_test_suite/error.import_json_reversed_surrogate.jsonnet.golden

@@ -0,0 +1,2 @@
+sjsonnet.ParseError: Expected "\"":1:10, found "\\uDE00\\uD8"
+    at [<root>].(error.import_json_reversed_surrogate.jsonnet:1:1)

sjsonnet/test/src/sjsonnet/JsonImportFastPathTests.scala

@@ -97,6 +97,35 @@ object JsonImportFastPathTests extends TestSuite {
       }
     }
 
+    test("invalid unicode surrogate exceptions fall back without internal errors") {
+      val inputs = Map(
+        "high-before-non-low-escape.json" -> "{\"key\":\"\\uD800\\u0041\"}",
+        "duplicate-high.json" -> "{\"key\":\"\\uD800\\uD801\"}",
+        "lone-low.json" -> "{\"key\":\"before\\uDC00after\"}",
+        "reversed.json" -> "{\"key\":\"\\uDE00\\uD83D\"}"
+      )
+
+      inputs.foreach { case (fileName, json) =>
+        val result = eval(Map(fileName -> json), s"""import "$fileName"""")
+        assert(result.isLeft)
+        result match {
+          case Left(error) =>
+            assert(error.startsWith("sjsonnet.ParseError"))
+            assert(!error.contains("Internal Error"))
+          case Right(_)    => assert(false)
+        }
+      }
+    }
+
+    test("valid unicode surrogate pairs stay on the json fast path") {
+      val files = Map(
+        "unicode.json" -> "{\"emoji\":\"\\uD83D\\uDE00\"}"
+      )
+
+      eval(files, """import "unicode.json"""") ==>
+      Right(ujson.Obj("emoji" -> "\uD83D\uDE00"))
+    }
+
     test("deep json imports keep parser recursion guard") {
       val files = Map("deep.json" -> """[[[]]]""")