Add array parser error tests

Agent-Logs-Url: https://github.com/wesleyel/swiftui-math/sessions/56436444-e15b-4dd0-8a70-c87df1e3dc4e

Co-authored-by: wesleyel <48174882+wesleyel@users.noreply.github.com>

Tests/SwiftUIMathTests/Internal/Syntax/ParserTests.swift

@@ -1089,6 +1089,28 @@ struct ParserTests {
     #expect(latex.contains("\\right."))
   }
 
+  @Test
+  func arrayRejectsInvalidColumnFormat() throws {
+    let str = "\\begin{array}{xyz}a\\end{array}"
+    var error: Math.ParserError? = nil
+
+    let list = Math.Parser.build(fromString: str, error: &error)
+
+    #expect(list == nil)
+    #expect(error?.code == .invalidEnvironment)
+  }
+
+  @Test
+  func arrayRejectsTooFewColumnSpecifiers() throws {
+    let str = "\\begin{array}{l}a&b\\end{array}"
+    var error: Math.ParserError? = nil
+
+    let list = Math.Parser.build(fromString: str, error: &error)
+
+    #expect(list == nil)
+    #expect(error?.code == .invalidNumberOfColumns)
+  }
+
   @Test
   func defaultTable() throws {
     let str = "x \\\\ y"