REPL: fix open parenthesis not triggering "incomplete"

Check if all of the syntax errors are at EOF, not that there's a single one.
In case of open parenthesis two syntax errors are reported for some reason

compiler/testData/repl/multiline/functionOnSeveralLines.repl

@@ -0,0 +1,6 @@
+>>> fun get7() =
+...     4 +
+...     2 +
+...     1
+>>> get7()
+7

compiler/testData/repl/multiline/multilineFunctionInvocation.repl

@@ -0,0 +1,10 @@
+>>> fun concat(a: String, b: String, c: String, d: String) = "$a$b$c$d"
+>>> concat(
+...     "hel",
+...     "lo"
+...     ,
+...     "wo" +
+...     "r", "l" +
+...     "d"
+... )
+helloworld

compiler/testData/repl/multiline/openParenthesisIncomplete.repl

@@ -0,0 +1,4 @@
+>>> fun sum(x: Int, y: Int) = x + y
+>>> sum(
+... 23,19)
+42

compiler/testData/repl/multiline/simpleFunctionBodyOnNextLine.repl

@@ -0,0 +1,4 @@
+>>> fun clock() =
+...     12
+>>> clock()
+12