Add theme handling to error pages

[martinRenou]

Code changes

Add theme handling to error pages. Also fixes an issue mentioned in #1107 where the error page fails to render due to include_css function not being defined.

User-facing changes

Error pages should be improved visually.

Backwards-incompatible changes

None

[github-actions]

👈 Launch a Binder on branch martinRenou/voila/improve_error_handling

[martinRenou]

Please update galata references

[github-actions]

Benchmark report

The execution time (in milliseconds) are grouped by test file, test type and browser.
For each case, the following values are computed: min <- [1st quartile - median - 3rd quartile] -> max.

Results table

Test file	voila-tree-classic.ipynb	voila-tree-light.ipynb	voila-tree-dark.ipynb	voila-tree-miami.ipynb	basics.ipynb	bqplot.ipynb	dashboard.ipynb	gridspecLayout.ipynb	interactive.ipynb	ipympl.ipynb	ipyvolume.ipynb	multiple_widgets.ipynb	query-strings.ipynb	reveal.ipynb
Render
chromium
actual	79 <- [85 - 97 - 121] -> 186	74 <- [79 - 88 - 109] -> 156	68 <- [70 - 77 - 88] -> 122	67 <- [72 - 78 - 93] -> 129	2471 <- [2579 - 2649 - 2717] -> 2983	2510 <- [2559 - 2570 - 2649] -> 2843	2655 <- [2737 - 2748 - 2868] -> 3234	3167 <- [3231 - 3307 - 3475] -> 3495	1985 <- [1994 - 2004 - 2007] -> 2133	3692 <- [3766 - 3777 - 3812] -> 4171	7252 <- [8966 - 9568 - 9597] -> 10417	9807 <- [9830 - 9842 - 9871] -> 10388	1467 <- [1474 - 1483 - 1555] -> 1609	2368 <- [2378 - 2397 - 2401] -> 2548
expected	3379 <- [3442 - 3517 - 3701] -> 3876	2976 <- [3227 - 3321 - 3421] -> 3604	3608 <- [3623 - 3709 - 3793] -> 3825	4453 <- [4453 - 4523 - 4661] -> 4748	2559 <- [2655 - 2656 - 2660] -> 2674	3982 <- [4079 - 4213 - 4356] -> 4743	12183 <- [18509 - 19553 - 20811] -> 21515	15319 <- [15660 - 15796 - 15912] -> 16056	1517 <- [1920 - 1997 - 2103] -> 2113

❗ Test metadata have changed

--- /dev/fd/63	2022-03-10 13:20:13.757197414 +0000
+++ /dev/fd/62	2022-03-10 13:20:13.757197414 +0000
@@ -4,37 +4,37 @@
     "BENCHMARK_REFERENCE": "actual"
   },
   "browsers": {
-    "chromium": "97.0.4666.0"
+    "chromium": "94.0.4595.0"
   },
   "systemInformation": {
     "cpu": {
-      "brand": "Xeon® Platinum 8272CL",
+      "brand": "Xeon® E5-2673 v3",
       "cache": {
         "l1d": 65536,
         "l1i": 65536,
-        "l2": 2097152,
-        "l3": 36700160
+        "l2": 524288,
+        "l3": 31457280
       },
       "cores": 2,
       "family": "6",
-      "flags": "fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology cpuid pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowprefetch invpcid_single pti fsgsbase bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx avx512f avx512dq rdseed adx smap clflushopt avx512cd avx512bw avx512vl xsaveopt xsavec xsaves md_clear",
+      "flags": "fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology cpuid pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm invpcid_single pti fsgsbase bmi1 avx2 smep bmi2 erms invpcid xsaveopt md_clear",
       "governor": "",
       "manufacturer": "Intel®",
-      "model": "85",
+      "model": "63",
       "physicalCores": 2,
       "processors": 1,
       "revision": "",
       "socket": "",
-      "speed": 2.6,
+      "speed": 2.4,
       "speedMax": null,
       "speedMin": null,
-      "stepping": "7",
+      "stepping": "2",
       "vendor": "GenuineIntel",
       "virtualization": false,
       "voltage": ""
     },
     "mem": {
-      "total": 7284850688
+      "total": 7291699200
     },
     "osInfo": {
       "arch": "x64",
@@ -42,11 +42,11 @@
       "codename": "Focal Fossa",
       "codepage": "UTF-8",
       "distro": "Ubuntu",
-      "kernel": "5.11.0-1028-azure",
+      "kernel": "5.8.0-1040-azure",
       "logofile": "ubuntu",
       "platform": "linux",
-      "release": "20.04.4 LTS",
-      "serial": "6fe698402f044602bf038833560abb94",
+      "release": "20.04.3 LTS",
+      "serial": "cfc067bfcb844f35865e279a1b0e66c5",
       "servicepack": "",
       "uefi": false
     }

[martinRenou]

1ba7791 commit should fix #1107. It is unclear to me why the jupyter_server.base.handlers.FileFindHandler is even trying to render the base.html template, that seems wrong?

[martinRenou]

@trungleduc I added a small docstring and did a bit of refactoring

[jtpio]

Looks good, thanks!

[jtpio]

@trungleduc I'll let have a second look and merge if this looks good to you, thanks!

[trungleduc]

Thanks @martinRenou !