Crash when using automation with ReaLearn parameters

[helgoboss]

When drawing some envelopes using ReaLearn's built-in parameters and then changing to Latch (maybe also other automation mode), this error occurs and REAPER even crashes (also see user issue #43):

Module name:         ReaLearn
Module version:      v1.12.0-pre6/x86_64 rev f505d4 (2020-12-08 01:30:21 UTC)
Module base address: 0x7ffac8170000
Module size:         0xa03000

Message: already mutably borrowed: BorrowError

   0:     0x7ffac8771e0d - Extended
   1:     0x7ffac876f9d9 - Extended
   2:     0x7ffac86845b8 - MAIN
   3:     0x7ffac878fe78 - Extended
   4:     0x7ffac878f9cf - Extended
   5:     0x7ffac87a2d70 - rust_eh_personality
   6:     0x7ffac87a2bd3 - rust_eh_personality
   7:     0x7ffac8335a55 - MAIN
   8:        0x140813c4e - <unknown>
   9:        0x14034f2da - <unknown>
  10:        0x1402705e5 - <unknown>
  11:        0x1402702f2 - <unknown>
  12:        0x140191880 - <unknown>
  13:        0x140190ab4 - <unknown>
  14:        0x1403aadef - <unknown>
  15:     0x7ffb1e672920 - ScreenToClient
  16:     0x7ffb1e6720c2 - ScreenToClient
  17:     0x7ffb1e6b9f89 - UnpackDDElParam
  18:     0x7ffb1e66e858 - CallWindowProcW
  19:     0x7ffb1e66e299 - DispatchMessageW
  20:        0x1403a4811 - <unknown>
  21:        0x140861391 - <unknown>
  22:     0x7ffb1e5b7034 - BaseThreadInitThunk
  23:     0x7ffb2057d0d1 - RtlUserThreadStart
--- cut ---

[helgoboss]

Backtrace with symbols resolved:

Attempting to resolve symbols for 24 addresses
==============================================
        
0: 7ffac8771e0d
-----------------------------------
            
Relative: Some(601e0d)
Ours absolute: Some(7ffac8771e0d)

7ffac8771d80
backtrace::backtrace::trace<closure-0>
C:\Users\runneradmin\.cargo\registry\src\github.com-1ecc6299db9ec823\backtrace-0.3.53\src\backtrace\mod.rs (line 53)


1: 7ffac876f9d9
-----------------------------------
            
Relative: Some(5ff9d9)
Ours absolute: Some(7ffac876f9d9)

7ffac876f980
backtrace::capture::Backtrace::new
C:\Users\runneradmin\.cargo\registry\src\github.com-1ecc6299db9ec823\backtrace-0.3.53\src\capture.rs (line 140)


2: 7ffac86845b8
-----------------------------------
            
Relative: Some(5145b8)
Ours absolute: Some(7ffac86845b8)

7ffac8684580
reaper_high::log_util::create_reaper_panic_hook::{{closure}}<closure-0>
C:\Users\runneradmin\.cargo\git\checkouts\reaper-rs-d32fed07113e6874\7596234\main\high\src\log_util.rs (line 51)


3: 7ffac878fe78
-----------------------------------
            
Relative: Some(61fe78)
Ours absolute: Some(7ffac878fe78)

7ffac878fd10
std::panicking::rust_panic_with_hook
/rustc/a74d1862d4d87a56244958416fd05976c58ca1a8\/src\libstd\panicking.rs (line 481)


4: 7ffac878f9cf
-----------------------------------
            
Relative: Some(61f9cf)
Ours absolute: Some(7ffac878f9cf)

7ffac878f940
std::panicking::begin_panic_handler
/rustc/a74d1862d4d87a56244958416fd05976c58ca1a8\/src\libstd\panicking.rs (line 385)


5: 7ffac87a2d70
-----------------------------------
            
Relative: Some(632d70)
Ours absolute: Some(7ffac87a2d70)

7ffac87a2d40
core::panicking::panic_fmt
/rustc/a74d1862d4d87a56244958416fd05976c58ca1a8\/src\libcore\panicking.rs (line 89)


6: 7ffac87a2bd3
-----------------------------------
            
Relative: Some(632bd3)
Ours absolute: Some(7ffac87a2bd3)

7ffac87a2b40
core::option::expect_none_failed
/rustc/a74d1862d4d87a56244958416fd05976c58ca1a8\/src\libcore\option.rs (line 1272)


7: 7ffac8335a55
-----------------------------------
            
Relative: Some(1c5a55)
Ours absolute: Some(7ffac8335a55)

7ffac8335980
realearn::infrastructure::plugin::realearn_plugin_parameters::{{impl}}::get_parameter
D:\a\realearn\realearn\main\src\infrastructure\plugin\realearn_plugin_parameters.rs (line 118)


15: 7ffb1e672920
-----------------------------------
            
Relative: None
Ours absolute: None

7ffb1e671d60
ScreenToClient


16: 7ffb1e6720c2
-----------------------------------
            
Relative: None
Ours absolute: None

7ffb1e671d60
ScreenToClient


17: 7ffb1e6b9f89
-----------------------------------
            
Relative: None
Ours absolute: None

7ffb1e6b9630
UnpackDDElParam


18: 7ffb1e66e858
-----------------------------------
            
Relative: None
Ours absolute: None

7ffb1e66e460
CallWindowProcW


19: 7ffb1e66e299
-----------------------------------
            
Relative: None
Ours absolute: None

7ffb1e66e040
DispatchMessageW


22: 7ffb1e5b7034
-----------------------------------
            
Relative: None
Ours absolute: None

7ffb1e5b7020
BaseThreadInitThunk


23: 7ffb2057d0d1
-----------------------------------
            
Relative: None
Ours absolute: None

7ffb2057d0b0
RtlUserThreadStart

[helgoboss]

Seems to happen only if mapping window open and automation mode set to latch. The REAPER crash occurs because at the moment we don't catch_unwind the panic - this is the first thing we should introduce.

Even better backtrace:

       9:     0x7ffaa159fd91 - core::result::Result<core::cell::RefMut<realearn::application::session::Session>, core::cell::BorrowMutError>::expect<core::cell::RefMut<realearn::application::session::Session>,core::cell::BorrowMutError>
                                   at C:\Users\benja\.rustup\toolchains\nightly-2020-05-15-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libcore\result.rs:963
      10:     0x7ffaa17cec30 - core::cell::RefCell<realearn::application::session::Session>::borrow_mut<realearn::application::session::Session>
                                   at C:\Users\benja\.rustup\toolchains\nightly-2020-05-15-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libcore\cell.rs:878
      11:     0x7ffaa18ecf50 - realearn::infrastructure::plugin::realearn_plugin_parameters::{{impl}}::set_parameter
                                   at C:\Users\benja\Documents\projects\dev\realearn-rs\main\src\infrastructure\plugin\realearn_plugin_parameters.rs:126
      12:     0x7ffaa23994fb - vst::interfaces::set_parameter
                                   at C:\Users\benja\.cargo\git\checkouts\vst-rs-8c46934a2d9a5311\8cb5571\src\interfaces.rs:59
      13:        0x14080a0a3 - <unknown>
      14:        0x140346442 - <unknown>
      15:        0x140344778 - <unknown>
      16:        0x14036b1b1 - <unknown>
      17:        0x1406ee8fd - <unknown>
      18:        0x1406f68a7 - <unknown>
      19:        0x1406ed1c8 - <unknown>
      20:        0x1404ccca9 - <unknown>
      21:        0x1404cb399 - <unknown>
      22:        0x1404ca443 - <unknown>
      23:        0x14003e0ea - <unknown>
      24:        0x140856087 - <unknown>
      25:        0x14085615f - <unknown>
      26:     0x7ffb1e5b7034 - BaseThreadInitThunk
      27:     0x7ffb2057d0d1 - RtlUserThreadStart
    , message: already borrowed: BorrowMutError