Prevent NumberFormatException on ill-formed unicode escape

Author: fmeum

klaxon/src/main/kotlin/com/beust/klaxon/Lexer.kt

@@ -126,7 +126,11 @@ class Lexer(passedReader: Reader, val lenient: Boolean = false): Iterator<Token>
                                     throw KlaxonException("EOF reached in unicode char after: u$unicodeChar")
                                 }
 
-                                val intValue = java.lang.Integer.parseInt(unicodeChar.toString(), 16)
+                                val intValue = try {
+                                    java.lang.Integer.parseInt(unicodeChar.toString(), 16)
+                                } catch(e: NumberFormatException) {
+                                    throw KlaxonException("Failed to parse unicode char: u$unicodeChar")
+                                }
                                 currentValue.append(intValue.toChar())
                             }
                             else -> currentValue.append(c)

klaxon/src/test/kotlin/com/beust/klaxon/JazzerTest.kt

@@ -32,4 +32,10 @@ class JazzerTest {
         val json = "\"\\u"
         Parser.default().parse(StringBuilder(json))
     }
+
+    @Test(expectedExceptions = [KlaxonException::class])
+    fun nonNumericUnicodeEscape() {
+        val json = "\"\\u\\\\{["
+        Parser.default().parse(StringBuilder(json))
+    }
 }