Fix .app method

[MarcSkovMadsen]

Adresses #3014

It works

[codecov]

Codecov Report

Merging #3047 (3ebebcd) into master (ced61b8) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3047      +/-   ##
==========================================
- Coverage   83.27%   83.26%   -0.01%     
==========================================
  Files         190      190              
  Lines       25001    25001              
==========================================
- Hits        20819    20817       -2     
- Misses       4182     4184       +2     

Impacted Files	Coverage Δ
panel/io/server.py	73.63% <100.00%> (ø)
panel/io/reload.py	69.23% <0.00%> (-2.20%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ced61b8...3ebebcd. Read the comment docs.