https://github.com/fish-shell/fish-shell/commit/5dc78dd858c28dcfd564ee50e56ccd33fc0b39dc

fix regression involving `read` from scripts

diff --git a/src/input.cpp b/src/input.cpp
index 1cdb151b3..d4dc16698 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -189,7 +189,7 @@ static std::vector<terminfo_mapping_t> terminfo_mappings;
 /// List of all terminfo mappings.
 static std::vector<terminfo_mapping_t> mappings;
 
-/// Set to true when the input subsytem has been initialized.
+/// Set to true when the input subsystem has been initialized.
 bool input_initialized = false;
 
 /// Initialize terminfo.
@@ -307,7 +307,6 @@ void init_input() {
     }
 
     input_initialized = true;
-    return;
 }
 
 void input_destroy() {
diff --git a/src/reader.cpp b/src/reader.cpp
index bd278ad6a..1e0e05698 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -1563,10 +1563,10 @@ static bool check_for_orphaned_process(unsigned long loop_count, pid_t shell_pgi
 
 /// Initialize data for interactive use.
 static void reader_interactive_init() {
-    assert(input_initialized);
     // See if we are running interactively.
     pid_t shell_pgid;
 
+    if (!input_initialized) init_input();
     kill_init();
     shell_pgid = getpgrp();
 
diff --git a/tests/read.in b/tests/read.in
index febc2968f..0fe31ec01 100644
--- a/tests/read.in
+++ b/tests/read.in
@@ -191,3 +191,6 @@ end
 if test (string length "$x") -ne $FISH_READ_BYTE_LIMIT
     echo reading the max amount of data with --nchars failed the length test
 end
+
+echo '# Confirm reading non-interactively works (#4206 regression)'
+echo abc\ndef | ../test/root/bin/fish -i -c 'read a; read b; show $a; show $b'
diff --git a/tests/read.out b/tests/read.out
index d35a9146a..88b445a40 100644
--- a/tests/read.out
+++ b/tests/read.out
@@ -58,3 +58,8 @@ newline
 
 # chunked read tests
 Chunked reads test pass
+# Confirm reading non-interactively works (#4206 regression)
+count=1
+|abc|
+count=1
+|def|