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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: Joannis

Sources/_NIOJSON/Core/JSONDescription.swift

@@ -942,7 +942,9 @@ extension JSONDescriptionProtocol {
                     // Quick length check first - most common rejection path
                     // For object keys with hash, use hash comparison to skip mismatches
                     if keyType == .objectKey || keyType == .objectKeyWithEscaping {
-                        let storedHash: UInt32 = self.getInteger(at: offset + Constants.objectKeyHashOffset) ?? 0
+                        guard let storedHash: UInt32 = self.getInteger(at: offset + Constants.objectKeyHashOffset) else {
+                            fatalError("JSONDescription index structure corrupted: missing object key hash at offset \(offset + Constants.objectKeyHashOffset)")
+                        }
                         // Only do memcmp if hashes match (fast reject on mismatch)
                         if storedHash == searchHash {
                             if memcmp(key.baseAddress!, json + Int(bounds.offset), Int(bounds.length)) == 0 {
@@ -986,8 +988,8 @@ extension JSONDescriptionProtocol {
                         }
                     } else if bounds.length == keySize {
                         if keyType == .objectKey || keyType == .objectKeyWithEscaping {
-                            let storedHash: UInt32 = self.getInteger(at: offset + Constants.objectKeyHashOffset) ?? 0
-                            if storedHash == searchHash {
+                            if let storedHash: UInt32 = self.getInteger(at: offset + Constants.objectKeyHashOffset),
+                               storedHash == searchHash {
                                 if memcmp(key.baseAddress!, json + Int(bounds.offset), Int(bounds.length)) == 0 {
                                     return (index, offset)
                                 }

Tests/IkigaJSONTests/JSONTests.swift

@@ -1751,8 +1751,10 @@ final class IkigaJSONTests: XCTestCase {
     }
 
     func testEmptyObjectKey() throws {
-        // Test case for potential bug: empty keys (keyLength = 0) cause invalid range 1...0
-        // This tests the hash computation loop in JSONParser+Parsing.swift line 331
+        // Regression test for empty keys (keyLength = 0): the hash computation loop uses
+        // a range like 1..<(keyLength + 1), which becomes 1..<1 (a valid empty range).
+        // This guards against changes that might introduce an invalid range (e.g. 1...keyLength)
+        // and ensures the parser correctly handles empty object keys.
         let json = """
         {"": "value"}
         """.data(using: .utf8)!