fix: default to ContinuousTimeseries for symbol not in SymbolCache

src/symbol_cache.jl

@@ -130,6 +130,14 @@ function timeseries_parameter_index(sc::SymbolCache, sym)
         return get(sc.timeseries_parameters, sym, nothing)
     end
 end
+
+for symT in [Any, Expr, AbstractArray]
+    @eval function get_all_timeseries_indexes(
+            ::SymbolCache{Nothing, Nothing, Nothing}, ::$symT)
+        Set([ContinuousTimeseries()])
+    end
+end
+
 function get_all_timeseries_indexes(sc::SymbolCache, sym)
     if is_variable(sc, sym) || is_independent_variable(sc, sym)
         return Set([ContinuousTimeseries()])

test/symbol_cache_test.jl

@@ -123,3 +123,8 @@ sc2 = copy(sc)
 @test sc.variables == sc2.variables
 @test sc.parameters == sc2.parameters
 @test sc.independent_variables == sc2.independent_variables
+
+sc = SymbolCache()
+for sym in [1, :a, :(a + b), "foo", [:a, :b], [:(a + b), :c]]
+    @test only(get_all_timeseries_indexes(sc, sym)) == ContinuousTimeseries()
+end