document-database

See #1029

• existence_error for an unknown flag
• syntax_error('disallowed: <shortflag>=<value>') when passing -c=true (terminusdb/terminusdb#1216)

Right now in insertElementRecursive(), DocLayer does NOT try to store arrays with null values as sparse arrays, i.e. for null value it still insert a k-v for it, which is kind of against what it attempts to achieve later when doing update (skipping the null values and effectively store those arrays as spars arrays). We should make the behavior consistent and do the same in insertion.

{testthat} 3.0.0 was released in October 2020, and some functionality {uptasticsearch} uses from it is now considered deprecated.

From the {testthat} vignettes on v3.x (link), the following are deprecated and may be removed in a future major release:

• `testthat::context(