Mixed spaces and tabs in indentions

[PropGit]

Here's a situation the results in a mix of tabs and spaces in an indent - disastrous.

There's source code somewhere outside the editor (maybe web page, maybe a text editor) that includes a tab followed by spaces within an indent of a line. Copying and pasting that code into the online editor doesn't result in the space being converted; in fact, it seems an even stranger mix of spaces and tabs results in that line's indent. Although the code still appears fine on screen (in online editor), it won't work properly on the micro:bit.