From f6f4ebfa890ceda870f62ecdb22f583a7a3dda5a Mon Sep 17 00:00:00 2001
From: Daniel Resnick <danielresnick@anthropic.com>
Date: Wed, 16 Apr 2025 18:10:56 -0600
Subject: [PATCH] Fix crashes due to forced unwrapping

---
 Sources/SwiftMath/MathRender/MTMathListBuilder.swift | 9 ++++++---
 Tests/SwiftMathTests/MTMathListBuilderTests.swift    | 4 +++-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/Sources/SwiftMath/MathRender/MTMathListBuilder.swift b/Sources/SwiftMath/MathRender/MTMathListBuilder.swift
index 3b146c9..26e713d 100755
--- a/Sources/SwiftMath/MathRender/MTMathListBuilder.swift
+++ b/Sources/SwiftMath/MathRender/MTMathListBuilder.swift
@@ -289,8 +289,11 @@ public struct MTMathListBuilder {
                     return list
                 } else {
                     // Create a new table with the current list and a default env
-                    let table = self.buildTable(env: nil, firstList: list, isRow: false)
-                    return MTMathList(atom: table!)
+                    if let table = self.buildTable(env: nil, firstList: list, isRow: false) {
+                        return MTMathList(atom: table)
+                    } else {
+                        return nil
+                    }
                 }
             } else if spacesAllowed && char == " " {
                 // If spaces are allowed then spaces do not need escaping with a \ before being used.
@@ -720,7 +723,7 @@ public struct MTMathListBuilder {
                 return nil
             }
             if env! != currentEnv!.envName {
-                let errorMessage = "Begin environment name \(currentEnv!.envName!) does not match end name: \(env!)"
+                let errorMessage = "Begin environment name \(currentEnv!.envName ?? "(none)") does not match end name: \(env!)"
                 self.setError(.invalidEnv, message:errorMessage)
                 return nil
             }
diff --git a/Tests/SwiftMathTests/MTMathListBuilderTests.swift b/Tests/SwiftMathTests/MTMathListBuilderTests.swift
index 5a9e3fb..f1453cb 100755
--- a/Tests/SwiftMathTests/MTMathListBuilderTests.swift
+++ b/Tests/SwiftMathTests/MTMathListBuilderTests.swift
@@ -187,7 +187,9 @@ final class MTMathListBuilderTests: XCTestCase {
                   ("\\begin{displaylines} x & y \\end{displaylines}", .invalidNumColumns),
                   ("\\begin{eqalign} x \\end{eqalign}", .invalidNumColumns),
                   ("\\nolimits", .invalidLimits),
-                  ("\\frac\\limits{1}{2}", .invalidLimits)
+                  ("\\frac\\limits{1}{2}", .invalidLimits),
+                  ("&\\begin", .characterNotFound),
+                  ("x & y \\\\ z & w \\end{matrix}", .invalidEnv)
             ]
     }