fix!: allow safe leverage operations during partial oracle outages

[toteki]

Description

This one does a lot of things:

• Allows account_summary to work during price outages, treating all unknown prices as zero.
  • In such cases, supplied value and other fields will appear lower than it really is, since some assets were skipped
  • Liquidation threshold will be null when it can't be computed, since there's no safe way to do that with missing prices
• borrow_limit in queries as well as messages is computed using only collateral with known prices
  • If the portion of your collateral with known prices is enough to cover a borrow, then it still works.
  • Same for withdraw and decollateralize
• MaxWithdraw and MaxBorrow (both queries and messages) now function with missing collateral prices, respecting the borrow limit policy above. The queries return zero on missing borrow prices, or a missing price for the specific token being asked for.
• liquidation_targets query skips addresses where liquidation threshold cannot be computed, instead of returning an error for the whole query
• MsgLiquidate will be able to function with some missing prices on the target's borrowed assets, if their other borrows are high enough to still put them above their liquidation threshold

API Breaking:

• liquidation_threshold field in account_summary field can now be null

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[codecov-commenter]

Codecov Report

Merging #1821 (5e3c211) into main (c500338) will increase coverage by 0.60%.
The diff coverage is 75.84%.

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@@            Coverage Diff             @@
##             main    #1821      +/-   ##
==========================================
+ Coverage   57.53%   58.13%   +0.60%     
==========================================
  Files          79       80       +1     
  Lines        8111     8213     +102     
==========================================
+ Hits         4667     4775     +108     
+ Misses       3104     3097       -7     
- Partials      340      341       +1     

Impacted Files	Coverage Δ
x/leverage/keeper/keeper.go	70.05% <56.25%> (+0.77%)	⬆️
x/leverage/keeper/iter.go	66.29% <62.50%> (+0.56%)	⬆️
x/leverage/keeper/borrows.go	77.44% <65.38%> (-0.34%)	⬇️
x/leverage/keeper/collateral.go	69.53% <66.66%> (-0.24%)	⬇️
x/leverage/keeper/limits.go	65.44% <75.00%> (+6.14%)	⬆️
x/leverage/keeper/msg_server.go	79.25% <75.00%> (+0.12%)	⬆️
x/leverage/keeper/oracle.go	67.83% <78.57%> (+3.49%)	⬆️
x/leverage/keeper/grpc_query.go	66.77% <82.85%> (+2.54%)	⬆️
x/leverage/client/tests/tests.go	100.00% <100.00%> (ø)
x/leverage/keeper/errors.go	100.00% <100.00%> (ø)
... and 9 more

[robert-zaremba]

I'm not sure if this is a right solution.
I'm worried about borrowed value will skip borrowed tokens with unknown oracle prices, treating them as zero value -- this can prevent liquidations, which normally should happen.

Also,

• proper error checks are missing.
• let's add a follow up task to test new edge cases
• document or make a task to solve panic in case of missing collateral price when we try to liquidate a position.
• probably, this will also block uncollaterize operations. Make sure we can decolaterize asset with "zero" price

[robert-zaremba]

pre-approving to make the planned released sooner.
I've updated the previous review note: #1821 (review)
Let's make sure we add all relevant tasks, and follow ups in the task board.

[toteki]

see , document or make a task to solve panic in case of missing collateral price when we try to liquidate a position.

This is an intended error return - we can't declare a borrower unhealthy (liquidation eligible) without knowing the value of all their collateral.

probably, this will also block uncollaterize operations.

Decollateralize and withdraw both use assertBorrowerHealth, which requires the value of all borrows is known, and that the borrow limit derived from their collateral with known prices (some might be missing) is sufficient to cover the borrows.

I'll check off the other two comments as they are done

[robert-zaremba]

Decollateralize and withdraw both use assertBorrowerHealth, which requires the value of all borrows is known, and that the borrow limit derived from their collateral with known prices (some might be missing) is sufficient to cover the borrows.

We should enable a user to decollaterize the asset with zero price.