Display math environment fails to parse if contained an isolated equal sign

[erratically]

⚠️ This issue respects the following points: ⚠️

• [x] This is a bug. Not a question or feature request.
• [x] The topic is not already reported at Issues. (I've searched it).
• [x] Markor is up to date. See Releases for the latest version. Updates are available from F-Droid and GitHub.
• [x] The bug is still present in the latest development version (git master). (Please download and try the test version of Markor, named Marder. Don't worry; Markor and Marder appear as completely separate applications. You can install both side-by-side, and Markor settings are not touched. In case the issue is resolved there, you don't need to create a bug report. The change will be part of the next Markor update.)

Description

In Markdown documents, in a display math environment (i.e. enclosed in a pair of $$) if an equal sign appears on a line by itself (possibly accompanied by whitespace characters only), the environment is not parsed correctly.

Steps to reproduce

Good

$$
(a + b )^2 = a^2 + b^2 + 2ab
$$

Bad

$$
(a + b )^2
\, =
a^2 + b^2 + 2ab
$$

Ugly

$$
(a + b )^2
=
a^2 + b^2 + 2ab
$$

Information

Android version: 15 Device: Samsung App Version: 2.14.1

Source

F-Droid

Format / File type

Markdown

Additional info / Log

Of course, one can avoid the issue by not placing the equal sign on a line of its own, but not all LLMs are there yet; and the issue is syntactic.

[gsantner]

Improvements are welcome. May be that KaTex, the library has an issue though.

[erratically]

1. This is also an issue for inline math (pairs of $ signs).
2. Github's MathJax only parses the first example correctly, but on www.mathjax.org/#demo they all are parsed correctly.
3. All examples are parsed correctly on the homepage of katex.org.

[gsantner]

You need to note it's embedded in Markdown, of course possible that it behaves differently in plain math syntax.

(as you noticed also on GitHub)