Errors while building bolt, while trying to fetch ppx_* libraries

[re-masashi]

I am trying to build bolt, however, it seems like there is some issue with dune or the dependencies.
Here is the error I am getting.

opam update

<><> Updating package repositories ><><><><><><><><><><><><><><><><><><><><><><>
[default] no changes from https://opam.ocaml.org
opam install . --deps-only
The following actions will be performed:
  - install ppx_js_style      v0.12.0
  - install ppx_inline_test   v0.12.0
  - install ppx_let           v0.12.0
  - install ppx_base          v0.12.0
  - install ppx_expect        v0.12.0
  - install ppx_bench         v0.12.0
  - install time_now          v0.12.0
  - install splittable_random v0.12.0
  - install ppx_module_timer  v0.12.0
  - install base_quickcheck   v0.12.1
  - install ppx_jane          v0.12.0
  - install base_bigstring    v0.12.0
  - install core_kernel       v0.12.3
  - install core              v0.12.4
===== 14 to install =====
Do you want to continue? [Y/n] y

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
-> retrieved base_bigstring.v0.12.0  (cached)
-> retrieved base_quickcheck.v0.12.1  (cached)
-> retrieved core.v0.12.4  (cached)
-> retrieved core_kernel.v0.12.3  (cached)
-> retrieved ppx_base.v0.12.0  (cached)
-> retrieved ppx_bench.v0.12.0  (cached)
-> retrieved ppx_expect.v0.12.0  (cached)
-> retrieved splittable_random.v0.12.0  (cached)
-> retrieved time_now.v0.12.0  (cached)

#=== ERROR while fetching sources for ppx_module_timer.v0.12.0 ================#
OpamSolution.Fetch_fail("End_of_file")

#=== ERROR while fetching sources for ppx_let.v0.12.0 =========================#
OpamSolution.Fetch_fail("End_of_file")

#=== ERROR while fetching sources for ppx_js_style.v0.12.0 ====================#
OpamSolution.Fetch_fail("End_of_file")

#=== ERROR while fetching sources for ppx_jane.v0.12.0 ========================#
OpamSolution.Fetch_fail("End_of_file")

#=== ERROR while fetching sources for ppx_inline_test.v0.12.0 =================#
OpamSolution.Fetch_fail("End_of_file")


<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
+- The following actions failed
| - fetch ppx_inline_test  v0.12.0
| - fetch ppx_jane         v0.12.0
| - fetch ppx_js_style     v0.12.0
| - fetch ppx_let          v0.12.0
| - fetch ppx_module_timer v0.12.0
+- 
- No changes have been performed
make: *** [Makefile:3: default] Error 40

I hope that you look after this soon.

[re-masashi]

For some information about the device,
OS: Arch Linux 5.18.5
Device: ThinkPad T410
Processor: Intel i5 M 520 (4) @ 2.400GHz
I got these errors without any modifications whatsoever.