Remove pre-parse for array-based JSON (PowerShell#15684)

Author: strawgate

src/Microsoft.PowerShell.Commands.Utility/commands/utility/WebCmdlet/JsonObject.cs

@@ -160,22 +160,6 @@ public static object ConvertFromJson(string input, bool returnHashtable, int? ma
             error = null;
             try
             {
-                // JsonConvert.DeserializeObject does not throw an exception when an invalid Json array is passed.
-                // This issue is being tracked by https://github.com/JamesNK/Newtonsoft.Json/issues/1930.
-                // To work around this, we need to identify when input is a Json array, and then try to parse it via JArray.Parse().
-
-                // If input starts with '[' (ignoring white spaces).
-                if (Regex.Match(input, @"^\s*\[").Success)
-                {
-                    // JArray.Parse() will throw a JsonException if the array is invalid.
-                    // This will be caught by the catch block below, and then throw an
-                    // ArgumentException - this is done to have same behavior as the JavaScriptSerializer.
-                    JArray.Parse(input);
-
-                    // Please note that if the Json array is valid, we don't do anything,
-                    // we just continue the deserialization.
-                }
-
                 var obj = JsonConvert.DeserializeObject(
                     input,
                     new JsonSerializerSettings

test/powershell/Modules/Microsoft.PowerShell.Utility/ConvertFrom-Json.Tests.ps1

@@ -58,7 +58,15 @@ Describe 'ConvertFrom-Json Unit Tests' -tags "CI" {
             $json | Should -BeOfType Hashtable
         }
     }
-
+    
+	It 'Throws an ArgumentException with an incomplete array with AsHashtable switch set to <AsHashtable>' -TestCase $testCasesWithAndWithoutAsHashtableSwitch {
+        Param($AsHashtable)
+        { ConvertFrom-Json '["1",' -AsHashtable:$AsHashtable } |
+            Should -Throw -ErrorId "System.ArgumentException,Microsoft.PowerShell.Commands.ConvertFromJsonCommand"
+        { ConvertFrom-Json '[' -AsHashtable:$AsHashtable } |
+            Should -Throw -ErrorId "System.ArgumentException,Microsoft.PowerShell.Commands.ConvertFromJsonCommand"
+    }
+	
     It 'Can convert multi-line object with AsHashtable switch set to <AsHashtable>' -TestCases $testCasesWithAndWithoutAsHashtableSwitch {
         Param($AsHashtable)
         $json = @('{"a" :', '"x"}') | ConvertFrom-Json -AsHashtable:$AsHashtable