[julia mode] Typing zero in front of numbers breaks code display and syntax highlighting

[Firionus]

I noticed this issue in Julia-Jupyter Notebooks and already wrongly reported it as a bug in IJulia:
JuliaLang/IJulia.jl#887
I was swiftly pointed here.

Minimal Example

• Open /demo/loadmode.html
• type "julia" in the lower text box and hit "change mode"
  • second line will change to "Current mode: julia"
• type 01 in the main editor text box
  • the 1 will not appear.
  • Further typing is almost impossible (except for writing one .)
  • The console (here Firefox) throws two errors:

Error: Mode julia failed to advance stream. codemirror.js:1174:11
    readToken file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:1174
    runMode file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:1228
    highlightLine file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:1074
    getLineStyles file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:1118
    buildLineContent file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:1751
    getLineContent file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:2141
    updateLineText file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:2149
    updateLineForChanges file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:2098
    patchDisplay file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:4218
    updateDisplayIfNeeded file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:4119
    endOperation_W1 file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:3827
    endOperations file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:3804
    endOperation file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:3793
    finishOperation file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:2053
    endOperation file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:3790
    runInOp file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:3919
    poll file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:9519
    init file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:9313
Error: Mode julia failed to advance stream. codemirror.js:1174:11
    readToken file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:1174
    runMode file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:1228
    highlightLine file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:1074
    highlightWorker file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:3968
    iterN file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:5624
    iterN file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:5736
    iter file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:6134
    highlightWorker file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:3964
    bind file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:148
    onTimeout file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:185
    bind file:///E:/ZickeZackeHühnerkacke/Codemirror Debugging/node_modules/codemirror/lib/codemirror.js:148

In the other issue I have detailed some breaking and non-breaking things to type:

Breaking Strings

• 01
• 02
• 06
• 00
• -01
• +01
• .01
• .02
• \01
• (01
• ?01
• =01
• 0,01 (no 1)
• 01. (one appears after hitting ".". Backspace needs to be hit two times to remove both dot and one)
• 00.01 (analogous with dot)
• 00a (only first zero appears)

Non-breaking Strings

• a01
• z04
• _01
• 0.2
• 0.0
• 0.01
• '01
• "01
• 0"1
• 0a
• 0'

Testing environment

CodeMirror v5.49.2 from npm, manually added /demo and /doc from Github master (a9789c7)
Firefox 71.0b9 and Chrome 78.0.3904.97
Windows 10 1903 Build 18362.418

Bug found in current Jupyter

>jupyter --version
jupyter core     : 4.6.1
jupyter-notebook : 6.0.2
qtconsole        : 4.5.5
ipython          : 7.9.0
ipykernel        : 5.1.3
jupyter client   : 5.3.4
jupyter lab      : not installed
nbconvert        : 5.6.1
ipywidgets       : 7.5.1
nbformat         : 4.4.0
traitlets        : 4.3.3

Likely cause

Seems to be a regression in 65fab82.
It was the last change to the code in the julia mode and replacing the julia.js with the one from the commit before (ff978a0) fixes the zeros-issue.