Unary dependency expected
See unary steps in the introduction to remind yourself that a unary step always represents exactly one value, typically an input to the GraphQL request (variables, context), a constant, or a derivative thereof.
Some steps may require that certain of their dependencies must be unary, this means that different values for this step do not need to be factored into batching, which can significantly simplify the logic. Typically this is used when the dependency is expected to either be a constant or something provided via GraphQL field arguments.
If you've received an error pointing to this webpage it is likely because the step in question has received a normal (non-unary) step where a unary step is expected. Depending on the reason this has occurred, there are a number of potential solutions.
Unary not required
Maybe when writing the step you used this.addUnaryDependency($step) by
mistake, and instead you meant the more general this.addDependency($step). If
so, simply fix your typo!
connection()
The connection() step expects first, last, offset, before and after
to be unary steps — this is because the GraphQL Cursor Connection
Specification only needs these values to be supplied via GraphQL field
arguments (which are unary) and so requiring them to be unary can simplify the
underlying collection logic. If you're received this error with a
connection() step, you're probably using the connection() step wrong;
consider re-reading its
documentation.